Coral reef transplant fraught with risks
| • | Chart: Repairing the damage |
By Jan TenBruggencate
Advertiser Science Writer
When drifting through the clear waters over a colorful coral garden, white is the color of something wrong.
Gregory Yamamoto • The Honolulu Advertiser
It's the color of broken coral heads, of crushed limestone, and it is the color of a large blotch of reef off Barbers Point where the 555-foot bulk carrier Cape Flattery went aground Feb. 2 and stayed for eight days.
This piece of antler coral was broken when the freighter Cape Flattery went aground Feb. 2.
"The white just jumps out at you," said John Naughton, a fisheries biologist with the National Oceanic and Atmospheric Administration.
The area that was immediately under the ship is now "a field of pulverized and polished rock. It's just totally scraped clean," he said. Nearby are slabs of hardened cement, the result of spills that occurred while the ship was being unloaded to lighten it.
Extending out in every direction is more damage: hundreds of overturned coral heads, some more than a century old, torn up by the ship's anchor and by tugboat tow cables that were used to control the Cape Flattery.
In very rough terms, the affected area is as much as 1,100 yards long and a third as wide. More than a week after the ship came off the reef, divers have been visiting the site daily to get a clear assessment of the damage, Naughton said. Extensive planning will be required for a long-term approach to recovery, but some work must be done immediately to save the big coral heads, many of which will die resting upside down without access to sunlight.
"There's been debate about that, but there's no doubt about it. You have to do it," said Billy Causey, superintendent of the Florida Keys National Marine Sanctuary.
Naughton said Causey's staff is probably the most experienced in the world at restoring coral reefs after ships have crushed them. Hawai'i officials have consulted with them in the past on how to prepare a reef for restoration, and how to cement coral back to the bottom.
Swells destructive
According to Naughton, the biggest coral transplanting project in the state was when 14 tons of coral heads were transplanted in the Big Island's Kawaihae Harbor in 1996. The process looked like a success for the first three months or so. Then came a big northwest swell.
Healthy reefs are valuable in many ways. They are crucial habitat for fish and other marine species and protect the coast from erosion. Living corals and coralline algae are constantly building up the reefs, upgrading that protection. "They support fisheries, tourism, recreation and culture. Native Hawaiian culture revolved around marine resources. They are enormously important," said Randy Kosaki, a marine biologist with the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve.
"They were just in too high-energy a place, and a majority was destroyed," he said.
Why reefs matter
Northwest swells can sweep into Barbers Point too, and there are other problems, said veteran reef researcher Jim Maragos, a U.S. Fish and Wildlife Service biologist who first transplanted corals as a graduate student in the early 1970s.
"This is the wrong time of year to be doing this" because of the likelihood of rough weather, Maragos said.
"In general, transplanting corals in a lagoon environment is feasible, but in open-ocean environments like Barbers Point, it's going to be more of a problem and will be expensive," he said.
But like Causey, Maragos said scientists have to do something.
With help and time, corals can heal themselves and firmly reattach to the bottom, "although they're not going to do it if there's really big wave action," Maragos said.
Off Barbers Point, teams of divers on Thursday began turning big coral heads upright so that the single-celled algae that live within coral polyps could receive sunlight. The teams will go back and try cementing these coral heads to the bottom later.
"We have GPS (satellite location) coordinates for each one," Maragos said.
Coral propped upright
State Division of Aquatic Resources reef scientist Dave Gulko said that for now, cementing work is being done in shallower water, while coral heads are being temporarily propped upright with rubble in water 60 feet deep or more to keep them alive until they can be cemented.
Photo courtesy NOAA Fisheries Service
Gulko said the state-federal teams are turning away volunteer divers who want to help because liability and legal issues require them to use divers with specialized training. A group from the University of Hawai'i diving safety program, which has such training, has joined in the reef-saving work, he said.
Damaged coral is shown on the seabed where the Cape Flattery ran aground off Barbers Point Harbor. Some work must be done immediately to save the big, old coral heads, many of which will die while upside down without access to sunlight, experts say.
Causey's top "reef doctor," Harold Hudson, said his work is mostly done in fairly shallow water. The Hawai'i teams have a special problem because the recommended fast-hardening cement-plaster mix for big coral heads would begin hardening before it can be lowered to sites at a depth of 50 feet or more.
So the teams are working with slower-hardening Portland cement and experimenting to see whether it will bond appropriately. The cement is mixed in a boat on the surface and passed to snorkelers who swim down to a halfway point, where it is handed off to divers.
At the bottom, the cement is pressed onto a surface that has been cleaned with a wire brush, and then a coral head is set carefully in place. Hudson of the Florida Keys sanctuary said there is no room for readjustment.
"Do not try to reposition coral after it has been pressed into place. This will introduce water between bonding surfaces and prevent attachment," he said.
The coral heads being placed upright and cemented in place are mostly in the areas at the periphery of the Cape Flattery grounding site. At the actual grounding location, there is virtually nothing left to work with.
Scientists will be watching the Barbers Point grounding site for many years, studying the success of the coral recovery, testing other reef regeneration methods, and learning about how a healthy Hawaiian reef recovers from devastating injury.
Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.
